对于北美板块的对流驱动运动的地震证据
David W Eaton1, Andrew Frederiksen
1Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada. deaton@uwo.ca
Nature
|March 23, 2007
概括
由于基底引的不确定性,板块构造的驱动力仍然存在争议. 对大流星热点轨迹的新分析揭示了向西的板底部移位,这表明星球流动驱动板运动.
科学领域:
- 地质物理学 地质物理学
- 构造物理学 构造物理学
- 板块构造学是一种板块构造学.
背景情况:
- 板块构造学的驱动力受到争论,基底引的不确定性阻碍了进展.
- 热点轨道提供了对过去板块运动和地幔合的洞察.
研究的目的:
- 研究北美板块表面和底部之间的相对运动.
- 使用热点轨道数据量化基底引对板块运动的影响.
主要方法:
- 分析北美东部大流星热点轨道的表面表达 (115-140 Myr).
- 表面轨道位置与板块重建模型和地震断层扫描进行比较,以推断在200公里深处的地幔结构.
主要成果:
- 在热点轨道的表面位置和其推断的深度位置之间发现了显著的错位.
- 这种错位随着年龄的增长而增加,表明板底相对于表面的向西移动在3.8 +/- 1.8 mm yr{-1}).
- 相对位移与地震快速轴和地幔流动保持一致,这表明天层流动影响了石质层基.
结论:
- 通过使用年龄限制的穿孔点,可以直接估计表面和底部之间的相对板块运动.
- 星球流动似乎会变形岩层基,作为北美板块运动的重要驱动力.
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